Method of making indirect bonding apparatus for orthodontic therapy

ABSTRACT

A method of making transfer apparatus for use in indirect bonding of orthodontic appliances includes the act of applying a spacer material over a dentition replica. The spacer material includes at least one cavity for releasably receiving an orthodontic appliance, and a base of the appliance is in contact with one of the teeth of the dentition replica. A tray is formed over the spacer material and the spacer material is then removed. Subsequently, a quantity of matrix material is directed into the space between the tray and the dentition replica in order to releasably hold the appliance for an indirect bonding procedure.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to method and apparatus for bonding orthodonticappliances such as brackets to a patient's teeth. The present inventionalso relates to methods for indirect bonding of orthodontic appliances.

2. Description of the Related Art

Orthodontic treatment involves movement of malpositioned teeth todesired locations in the oral cavity. Orthodontic treatment can improvethe patient's facial appearance, especially in instances where the teethare noticeably crooked or where the jaws are out of alignment with eachother. Orthodontic treatment can also enhance the function of the teethby providing better occlusion during mastication.

One common type of orthodontic treatment involves the use of tiny,slotted appliances known as brackets. The brackets are fixed to thepatient's teeth and an archwire is placed in the slot of each bracket.The archwire forms a track to guide movement of teeth to desiredlocations.

The ends of orthodontic archwires are often connected to smallappliances known as buccal tubes that are, in turn, secured to thepatient's molar teeth. In many instances, a set of brackets, buccaltubes and an archwire is provided for each of the patient's upper andlower dental arches. The brackets, buccal tubes and archwires arecommonly referred to collectively as “braces”.

In many types of orthodontic techniques, the precise position of theappliances on the teeth is an important factor for helping to ensurethat the teeth move to their intended final positions. For example, onecommon type of orthodontic treatment technique is known as the“straight-wire” technique, where the archwire lies in a horizontal planeat the conclusion of treatment. Consequently, if a bracket is attachedto the tooth at a location that is too close to the occlusal or outertip of the tooth, the orthodontist using a straight-wire technique willlikely find that the tooth in its final position is unduly intruded. Onthe other hand, if the bracket is attached to the tooth at a locationcloser to the gingiva than is appropriate, it is likely that the finalposition of the tooth will be more extruded than desired.

In general, orthodontic appliances that are adapted to be adhesivelybonded to the patient's teeth are placed and connected to the teeth byeither one of two techniques: a direct bonding technique, or an indirectbonding technique. In the direct bonding technique, the appliance andadhesive are grasped with a pair of tweezers or other hand instrumentand placed by the practitioner on the surface of the tooth in anapproximate desired location. Next, the appliance is shifted along thesurface of the tooth as needed until the practitioner is satisfied withits position. Once the appliance is in its precise, intended location,the appliance is pressed firmly onto the tooth to seat the appliance inthe adhesive. Excess adhesive in areas adjacent the base of theappliance is removed, and the adhesive is then allowed to cure and fixthe appliance firmly in place.

While the direct bonding technique described above is in widespread useand is considered satisfactory by many, there are shortcomings that areinherent with this technique. For example, access to surfaces ofmalposed teeth may be difficult. In some instances, and particularly inconnection with posterior teeth, the practitioner may have difficultyseeing the precise position of the bracket relative to the toothsurface. Additionally, the appliance may be unintentionally dislodgedfrom its intended location during the time that the excess adhesive isbeing removed adjacent the base of the appliance.

Another problem associated with the direct bonding technique describedabove concerns the significant length of time needed to carry out theprocedure of bonding each appliance to each individual tooth. Typically,the practitioner will attempt to ensure that each appliance ispositioned in its precise, intended location before the adhesive iscured, and some amount of time may be necessary before the practitioneris satisfied with the location of each appliance. At the same time,however, the patient may experience discomfort during the procedure andhave difficulty in remaining relatively motionless, especially if thepatient is an adolescent. As can be appreciated, there are aspects ofthe direct bonding technique that can be considered a nuisance for boththe practitioner and for the patient.

Indirect bonding techniques avoid many of the problems noted above. Ingeneral, indirect bonding techniques known in the past have involved theuse of a placement device or transfer apparatus having a shape thatmatches the configuration of at least part of the patient's dental arch.One type of placement device or transfer apparatus is often called a“transfer tray” and typically has a cavity for receiving a number ofteeth simultaneously. A set of appliances such as brackets arereleasably connected to the tray at certain, predetermined locations.

Other types of transfer apparatus used in indirect bonding are oftenreferred to as “jigs” and resemble a framework that contacts one or moreteeth at certain locations. For example, a jig constructed for use inbonding a single appliance to a single tooth may have an arm thatextends over and contacts an incisal section of the tooth. An appliancesuch as a bracket is releasably connected to the jig at a certain,predetermined location relative to the tooth.

During the use of orthodontic transfer apparatus for indirect bonding,an adhesive is typically applied to the base of each appliance by theorthodontist or a staff member. The device is then placed over thepatient's teeth and remains in place until such time as the adhesivehardens. Next, the apparatus is detached from the teeth as well as fromthe appliances, with the result that all of the appliances previouslyconnected to the apparatus are now bonded to respective teeth at theirintended, predetermined locations.

In more detail, one method of indirect bonding of orthodontic appliancesusing the transfer tray described above includes the steps of taking animpression of each of the patient's dental arches and then making areplica plaster or “stone” model from each impression. Next, theappliances are bonded to the stone models at desired locations.Optionally, the bonding adhesive can be a chemical curing adhesive (suchas Concise brand adhesive from 3M) or a light-curable adhesive (such asTransbond XT brand adhesive or Transbond LR brand adhesive from 3M).Optionally, the brackets may be adhesive precoated brackets such asthose described in U.S. Pat. Nos. 5,015,180, 5,172,809, 5,354,199 and5,429,229.

The transfer tray is then made by placing a matrix material over themodel as well as over the appliances placed in the model. For example, aplastic sheet matrix material may be held by a frame and exposed toradiant heat. Once the plastic sheet material has softened, it is placedover the model and the appliances. Air in the space between the sheetmaterial and the model is then evacuated, and the plastic sheet materialassumes a configuration that precisely matches the shape of the replicateeth of the stone model and attached appliances.

The plastic sheet matrix material is then allowed to cool and harden toform a tray. The tray and the appliances (which are embedded in aninterior wall of the tray) are then detached from the stone model. Ifthe cured adhesive that was used to bond the appliances to the stonemodel remains on the base of the appliances after detachment from thestone model, the adhesive serves as a “custom” base having a concavecontour that precisely replicates the convex contour of the previousattachment location of the stone model, as well as the convexconfiguration of the intended mounting location of the appliances on thepatient's teeth.

Once the patient has returned to the practitioner's office, a quantityof adhesive is placed on the base of each appliance, and the tray withthe embedded appliances is then placed over the matching portions of thepatient's dental arch. Since the configuration of the interior of thetray closely matches the respective portions of the patient's dentalarch, each appliance is ultimately positioned on the patient's teeth atprecisely the same location that corresponds to the previous location ofthe same appliance on the stone model.

Indirect bonding techniques offer a number of advantages over directbonding techniques. For one thing, and as indicated above, it ispossible to bond a plurality of appliances to a patient's dental archsimultaneously, thereby avoiding the need to bond each appliance inindividual fashion. In addition, the transfer apparatus helps to locatethe appliances in their proper, intended positions such that adjustmentof each appliance on the surface of the tooth before bonding is avoided.The increased placement accuracy of the appliances that is oftenafforded by indirect bonding techniques helps ensure that the patient'steeth are moved to their proper, intended positions at the conclusion oftreatment.

In recent years, many improvements have been made in the field ofindirect bonding. For example, U.S. Pat. No. 5,971,754 describes atwo-component indirect bonding adhesive with a relatively fast curingtime that reduces the length of time that the tray must be firmly heldagainst the patient's teeth. U.S. Pat. No. 6,123,544 describes atransfer tray that receives movable arms for placing appliances on thepatient's teeth once the tray is positioned in the oral cavity.Published U.S. patent application entitled “METHOD AND APPARATUS FORINDIRECT BONDING OF ORTHODONTIC APPLIANCES” (U.S. Publication No.2004-0219471, published on Nov. 4, 2004), describes among other things atransfer apparatus with an improved matrix material for releasablyholding appliances in place. Published U.S. patent application entitled“APPARATUS FOR INDIRECT BONDING OF ORTHODONTIC APPLIANCES AND METHOD OFMAKING THE SAME” (U.S. No. 2005-0074716, Apr. 7, 2005) describes amongother things a transfer apparatus that includes at least one appliancehaving a base with a contour that is a replica of a contour of aportions of the patient's tooth structure, and a bonding composition onthe base for bonding to the patient's tooth structure.

There is a continuing need in the art to improve the methods of makingtransfer apparatus. For example, it would be desirable to reduce theamount of time needed to make transfer apparatus. However, it is alsoimportant to ensure that any new methods of construction do notadversely affect the ultimate placement accuracy of the appliances onthe patient's teeth during a bonding procedure, so that the teeth aremoved to their proper, intended positions at the conclusion of thetreatment program.

SUMMARY OF THE INVENTION

The present invention is directed toward a method of constructingtransfer apparatus for orthodontic indirect bonding, wherein a spacermaterial is applied to a replica of the patient's dentition. The spacermaterial has at least one cavity for receiving an orthodontic appliance,and remains on the replica while a tray is formed over the spacermaterial. The cavity is located in the spacer material at a certain,pre-selected position, with the result that the appliance is ultimatelypositioned in its proper, intended location with respect to the replica.

In more detail, the present invention in one aspect concerns a method ofmaking transfer apparatus for orthodontic indirect bonding comprising:

providing a replica of a patient's dentition;

applying a spacer material over the replica of the patient's dentition,wherein the spacer material has at least one cavity;

placing an orthodontic appliance in a cavity of the spacer material inan orientation such that a base of the appliance is in contact with areplica tooth of the replica dentition; and

forming a tray over the spacer material.

In another aspect, the present invention concerns an assembly for makingtransfer apparatus for use in indirect bonding of orthodonticappliances. The assembly comprises:

a dentition replica including a number of replica teeth;

a spacer material extending over at least part of the replica includingat least part of the replica teeth, the spacer material having a numberof cavities each located next to one of the replica teeth;

a set of orthodontic appliances each located in a respective one of thecavities; and

a tray extending over the cavities and releasably connected to thespacer material.

In yet another aspect, the present invention concerns a method of makingtransfer apparatus for orthodontic indirect bonding that comprises:

providing a replica of a patient's dentition;

obtaining a set of digital data representing the shape of the patient'sdentition;

making a spacer material using the digital data in a rapid prototypingprocess;

applying the spacer material to the replica of the patient's dentition;and

forming a tray over the spacer material.

Additional aspects of the present invention are described in theparagraphs that follow and are illustrated in the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top and front view showing a physical replica of one dentalarch of an orthodontic patient, illustrating an example of a replica ofa patient's tooth structure and adjacent gingival tissue as they mightappear before the commencement of treatment;

FIG. 2 is a view of the dental arch replica shown in FIG. 1, along witha set of orthodontic appliances and spacer material that have beenapplied to the replica;

FIG. 3 is an enlarged side cross-sectional view of one of the replicateeth illustrated in FIG. 2 along with the appliance and spacermaterial;

FIG. 3 a is a view somewhat similar to FIG. 3 but showing an alternateembodiment of the invention;

FIG. 4 is a view somewhat similar to FIG. 3, additionally showing a traythat has been formed over the spacer material;

FIG. 5 is a view of the tooth structure replica illustrated in FIG. 1after the spacer material and the tray have been detached from thereplica, and additionally showing three stop members that have beenplaced along occlusal sections of the replica teeth;

FIG. 6 is an enlarged side cross-sectional view of one of the replicateeth, one of the appliances, and one of the stop members depicted inFIG. 5, and additionally showing a quantity of matrix material that hasbeen placed between the replica and the tray shown in FIG. 4 after thereplica and the tray have been inverted to make a transfer apparatus;

FIG. 7 is an enlarged side cross-sectional view illustrating the act ofapplying the transfer apparatus to one of the patient's teeth;

FIG. 8 is a view somewhat similar to FIG. 3 but in accordance withanother embodiment of the present invention; and

FIG. 9 is a view somewhat similar to FIG. 4 but in accordance with theembodiment illustrated in FIG. 8.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A method for indirect bonding of one or more orthodontic appliances inaccordance with one aspect of the present invention is depicted in FIGS.1-7. FIG. 1 illustrates a replica 20 of a portion of a dental arch of anorthodontic patient. For exemplary purposes, the replica 20 representsthe patient's lower dental arch. However, a replica of a patient's upperdental arch may be provided as an addition to or as an alternative tothe lower dental arch replica as shown. As a further option, the replica20 may represent only a portion of a dental arch, such as a quadrant ofan arch or only one or two teeth of a dental arch. In the exampleillustrated, the replica 20 includes a number of replica teeth 22,corresponding to each tooth of the patient's lower dental arch.

As one option, the replica 20 is made by first taking an impression ofthe patient's lower dental arch, using care to avoid undue distortion.An alginate impression material may be used, such as “Palgat” Plus brandalginate impression material from 3M Espe. Alternatively, a hydrocolloidor vinyl polysiloxane impression material may be used, such as “PositionPenta” brand vinyl polysiloxane impression material from 3M ESPE.

The model or replica 20 is then made from the impression. Optionally,the replica 20 is a “stone” model made from plaster of Paris, using careto avoid bubbles in the model. If small voids are present, the voids canbe filled with a small, additional quantity of plaster of Paris. As anoption, the replica 20 includes only the replica teeth 22 and sufficientreplica gingival tissue 24 to hold the replica teeth 22 together.

As an alternative, the replica 20 may be made using digital data that isrepresentative of the patient's teeth and adjacent gingival tissue. Thedigital data may be obtained by use of a hand-held intra-oral scanner orother device known in the art. As another option, the digital data maybe obtained by scanning an impression or a stone model. The replica 20may then be made from the digital data using, for example, a stereolithographic printer.

The replica 20 may also be made using digital data in conjunction with amilling process. For example, a CNC milling machine, similar to theCAD/CIM milling machines sold by Cerec Network of Buelach, Switzerland,may be used to mill replicas made of ceramic, composite or othermaterials. An intra-oral camera, similar to the cameras associated withthe Cerec machines, may be used to obtain digital data representing theshape of the dental arches. Alternatively, a scanner may be used to scanan impression or a model of an impression to obtain the digital data.

Preferably, the replica 20 is an accurate representation of thepatient's oral structure. In particular, the replica teeth 22 will havea configuration and orientation that are identical to the configurationand orientation of the corresponding teeth of the orthodontic patient.In addition, the replica gingival tissue 24 will have a shape thatmatches the shape of the corresponding portions of the gingival tissueof the patient.

A thin layer of a release agent is then applied to the replica 20 andallowed to dry. An example of a suitable release agent is a watersoluble polyvinyl alcohol, such as “PA0810” from PTM & W Company ofSanta Fe Springs, Calif.

Next, and as shown in FIGS. 2 and 3, a spacer material 26 is applied tothe replica 20. The spacer material 26 preferably comprises acustom-made material that is optionally formed using a rapid prototypingmethod. Examples of suitable rapid prototyping methods includestereolithography, thermojet printing and the like. Preferably, digitaldata representing the shape of a portion of the patient's dental arch isused in the rapid prototyping method to make the spacer material 26.

The spacer material 26 includes a number of pockets or cavities 28, eachof which has a shape adapted to complementally receive a correspondingorthodontic appliance 34. For example, if an orthodontic bracket isintended to be received in one of the cavities 28, such cavity 28optionally has an occlusal wall portion, a mesial wall portion, agingival wall portion, a distal wall portion and a facial wall portionthat match the configuration of the occlusal side, the mesial side, thegingival side, the occlusal side and the facial side respectively of thebracket. As another option, the gingival wall portion may be omitted tofacilitate subsequent removal of the transfer apparatus from thepatient's dental arch. Preferably, the cavities 28 include smallprotrusions that extend into and are complementally received in anarchwire slot, a vertical slot between tiewings, and/or other featuresof the appliance. The cavities 28 are constructed slightly smaller thanthe corresponding appliance 34 in order to each firmly hold theorthodontic appliance 34 in place. However, the spacer material 26 issufficiently flexible to enable the appliance 34 to be released from thecavity 28 when desired.

Each of the cavities 28 is positioned in a location that corresponds tothe subsequent desired location of an orthodontic appliance 34 on thedental arch. For instance, each of the cavities 28 may be positioned toplace the center of the appliance 34 in a location corresponding to thefacial axis point (or “FA” point) of the corresponding replica tooth 22,although other locations are also possible. As will be described below,the spacer material 26 functions to subsequently provide clearance inthe transfer apparatus for receiving the orthodontic appliances 34.

Preferably, the locations of the cavities 28 and consequently theultimate position of the placed appliance 34 are determined by computersoftware that has access to digital data representing a virtual model ofthe replica 20. The software preferably includes subprograms suitable toanalyze the existing malocclusion of the patient and select properappliances 34 for treatment of the particular malocclusion at hand. Oncethe appliances 34 are selected and the locations of the cavities 28 forreceiving the appliances are determined, the software instructsautomated apparatus (such as apparatus using the rapid prototypingmethod mentioned earlier) to make the spacer 26 in custom fashion.Optionally, the software enables the practitioner, patient or otherobserver to see on a monitor or other video output a virtualrepresentation of the patient's teeth as they should appear at theconclusion of treatment using the selected appliances 34 placed oncertain locations of the teeth.

Preferably, the software includes subprograms for selecting appliances34, analyzing malocclusions and/or predicting tooth movement and finalpositions of the teeth. An example of software for choosing appliances34 is described in published U.S. patent application no. 2003-0163291,Aug. 28, 2003 entitled “Selection of Orthodontic Brackets”, thedisclosure of which is expressly incorporated by reference herein.Optionally, the software includes subprograms for making customorthodontic appliances 34 using, for example, a computer numericalcontrol milling machine, instead of selecting appliances 34 from anexisting set of appliances as mentioned above. As an additional option,an orthodontic archwire may be placed in the slots of the appliances 34and ligated in place. This step serves to further reduce the patient'stime that is subsequently spent in the chair.

Preferably, the spacer material 26 extends over at least a majority ofthe facial surface area, the occlusal surface area and the lingualsurface area of the replica teeth 22. However, the spacer material 26may be omitted from contacting certain surfaces of the replica teeth 22if desired, such as the lingual surface area of the replica teeth 22. Inthe illustrated embodiment, the spacer material 26 extends over thereplica gingival tissue 24 as well as the lingual tooth areas.

Preferably, the spacer material 26 is provided as an integral unitarysection of material, such that separate handling of the two or moresections of material is avoided. However, other constructions are alsopossible. For example and as shown in FIG. 3 a, the spacer material 26 acould comprise a number of discrete, ring-shaped sections 27 a ofmaterial that each receive a corresponding appliance, along with aninitially separate preformed sheet 29 a of overlay material that isplaced over each ring-shaped section 27 a of material once thering-shaped sections 27 a are placed on the replica teeth 22.

The spacer material 26 can be any one of a number of materials such as athermoset material. A suitable material is a silicone material, such as“RTV 615” from General Electric. Other suitable materials include, forexample, materials used in rapid prototyping processes, such asthermoplastics (including nylons), thermoplastic elastomers andcomposites (e.g., glass-filled nylons). Examples of such materialsinclude “Sinterstation HiQ Series SLS System” brand materials (includingDuraForm brand PA polyamide nylon, DuraForm Brand GF glass-filled nylon,and Somos brand 201 materials), “Viper SLA” brand materials from 3DSystems (including Dreve Otoplatik Fototec brand SL materials and Accurabrand SL materials), and “Thermojet” brand materials (includingThermojet brand 88 and Thermojet brand 2000 materials). Optionally, thespacer material 26 may be temporarily held in place on the replica 20 byuse of an adhesive, such as a pressure sensitive adhesive. Preferably,the spacer material 26 is preformed and has the shape of the underlyingreplica dental arch when the spacer material 26 is relaxed.Alternatively, the spacer material 26 is formed to match the shape ofthe replica dental arch when it is applied to the latter. Optionally,the spacer material 26 is coated with a layer of pressure sensitiveadhesive on one side and initially connected to a sheet of releasematerial until such time as it is needed for use.

An orthodontic appliance 34 is received in each cavity 28 of the spacermaterial 26. In the embodiment illustrated in FIGS. 1-7, the orthodonticappliance 34 is a bracket, although other appliances such as buccaltubes, lingual sheaths, buttons and bondable bite openers are alsopossible. The appliances 34 may be placed in the cavities 28 eitherbefore or after the spacer material 26 is placed in contact with thereplica dental arch. However, if the appliances 34 are placed in thecavities 28 after the spacer material 26 is applied to the replicadental arch, the facial sides of the cavities 28 are initially open andthe spacer material 26 preferably includes an initially separatepreformed sheet of overlay material that covers the facial sides of thecavities 28 and the appliances 34 such that once the appliance has beenplaced in the cavity the facial side of the cavity is closed.

Before the appliances 34 are placed over the replica dental arch, aquantity of a composition 36 is placed between each appliance and thecorresponding replica tooth 22. Preferably, the composition 36 is alight-curable composition such as a light-curable adhesive, and theadhesive is coated across the base of each appliance 34. Preferably, theappliances 34 are adhesive precoated appliances that have a layer oflight-curable adhesive applied by the manufacturer to the base of eachappliance 34. Such adhesive coated appliances are described in U.S. Pat.Nos. 5,015,180, 5,172,809, 5,354,199 and 5,429,229, all of which areassigned to the assignee of the present invention. The appliances 34 maybe made of any suitable material such as metal (e.g., stainless steel),ceramic (e.g., translucent polycrystalline alumina) or plastic (e.g.,translucent polycarbonate).

If the appliances 34 are not precoated with adhesive by themanufacturer, a coating of composition 36 such as an orthodonticadhesive may be applied by the practitioner to the base of eachappliance 34. Suitable orthodontic adhesives include composites,compomers, glass ionomers and resin-modified glass ionomers. Examples oflight-curable adhesives include Transbond XT brand or Transbond LR brandadhesives from 3M Unitek. Examples of chemical curing adhesives includeConcise brand adhesive and Multi-Cure brand glass ionomer cement from 3MUnitek.

Next, the practitioner applies firm pressure to each appliance 34 inorder to ensure that each appliance 34 is firmly seated on thecorresponding replica tooth 22. The practitioner may apply fingerpressure directly to the facial side of the appliances 34.Alternatively, if the facial side of the appliances 34 is not covered bythe spacer material, the practitioner may use a scaler or other handinstrument to apply force to the archwire slot of each appliance 34.

Alternatively, the appliances 34 may be placed on the replica teeth 22by means of robotic equipment. For example, the robotic equipment mayinclude a gripping arm that is programmed to pick an appropriateappliance 34 from a set of appliances and place the selected appliance34 on the appropriate replica tooth 22. The robotic arm then proceeds tograsp another appliance 34 for placement on another replica tooth 22.Finally, the spacer material 26 is placed over the appliances 34 and thereplica arch 20.

The adhesive is shown in FIGS. 3-4 and 6-7 and is not necessarily drawnto scale. Initially, the adhesive 36 is only slightly hardened such thata tack cure is provided. In this manner, the appliances 34 will remainbonded to the replica teeth 22 when the spacer material 26 issubsequently removed, and yet the adhesive flash that extrudes from thesides of the appliance base remains relatively soft and can be removedwithout undue effort.

Subsequently, a tray 30 is formed over the spacer material 26 asillustrated in FIG. 4. Preferably, the tray 30 is shaped by vacuumforming a sheet of material over the sheet of spacer material 26. Asuitable material for the tray 30 is a sheet of polycarbonate such asMakrolon brand material from Bayer or Lexan brand polycarbonate from GEhaving a thickness of 0.06 inch. Other materials, such aspolyethyleneterephthalate glycol (“PETG”) may also be used. Heat isapplied during the vacuum forming process in order to facilitateconformance of the sheet to the external configuration of the spacermaterial 26.

Once the tray 30 has hardened, the tray 30 is detached from the spacermaterial 26. The spacer material 26 is then detached from the replica 20and the appliances 34 and set aside or discarded. During detachment ofthe spacer material 26 from the replica 20, the appliances 34 remainbonded to the replica teeth.

After the flash from excess adhesive 36 is removed from areas adjacentthe base of the appliances 34, the remaining adhesive is more fullycured. As one example, if the appliances 34 are made of metal or otheropaque material and if a light-curable adhesive 36 is used, it ispreferable to expose the replica 20 to the curing light for a relativelylong amount of time such as 3 to 5 minutes to ensure that the adhesive36 has sufficiently hardened. As an alternative to light curing chambersmentioned above, a hand-held curing unit may be used, such as OrtholuxXT brand curing unit from 3M Unitek.

As an additional option, the replica 20 including the replica teeth 22may be made from a material that transmits actinic radiation. Suitablematerials include epoxy resins that are transparent or translucent whenhardened. Preferably, the material is optically clear. An example of asuitable epoxy is E-CAST F-82 clear epoxy resin and No. 302 (or UCE-302)hardener, from United Resin Corporation. Other suitable materialsinclude polyesters and urethanes. The use of transparent or translucentmaterials is advantageous in instances where the appliances 34 are madeof opaque materials, since the actinic radiation can be transmittedthrough the replica 20 for curing portions of the adhesive 36 that arelocated adjacent the middle of the appliance base. Actinic radiation caninclude wavelengths in the visible range, ultraviolet range, infraredrange or any combination thereof, in accordance with the type ofphotoinitiator contained in the adhesive 36.

Excess portions of the tray 30 are then trimmed as desired. Next, stopmembers 39 are formed to facilitate subsequent positioning of thetransfer apparatus relative to the patient's teeth during a bondingprocedure. The stop members 39 may be made by placing curable materialon the replica 20 or alternatively within the channel of the tray 30.Preferably, once construction of the transfer apparatus 20 has beencompleted, the stop members 39 are located along the curved longitudinalaxis of the tray channel and next to the bottom wall portion of the tray30 that defines the channel.

In the illustrated embodiment, three spaced-apart stop members 39 aremade by placing curable material across occlusal sections of the replicadental arch 20. One stop member 39 is formed near the center of thereplica dental arch 20, while the other two stop members 39 are formednear the right end and left end respectively of the replica dental arch20. However, other constructions are possible. For example, a singlestop member 39 may be provided that extends along a substantial majorityof the curved longitudinal axis of the replica dental arch 20.Alternatively, two stop members 39 may be provided, each of whichextends along a majority of the left quadrant and the right quadrantrespectively of the replica dental arch 20 and follows the curvedlongitudinal axis of the arch. Additionally, or as an alternative toocclusal stop members, one or more stop members 39 may be provided alongthe lingual surfaces and/or the facial surfaces of the replica dentalarch 20. Lingual and facial stop members may be particularlyadvantageous to ensuring proper fitting and placement of the transferapparatus in instances when the patient's maloccluded teeth presentdiverging tooth angulations.

The stop members 39 may be made from a variety of materials. Suitablematerials include, for example, an orthodontic or dental adhesive, adental restorative material, or a bite registration material. An exampleof a suitable bite registration material is “Imprint Bite” biteregistration material from 3M Espe. Preferably, the stop members 39 aremade of a thermosetting material that, after hardening, does notsubstantially soften upon contact with heat. Preferably, the stopmembers 39 transmit actinic radiation and retain their shape overextended periods of time.

Next, the tray 30 is placed over the replica dental arch 20 includingthe unhardened stop members 39. The tray 30 is pressed toward thereplica arch 20 with sufficient force to deform the shape of theunhardened stop members 39 and bring the tray 30 to a desired positionrelative to the replica 20 as the stop members 39 are flattened. Thisdesired position is somewhat adjacent the replica 20, but issufficiently spaced from the replica 20 so that a quantity of matrixmaterial may be received between the tray 30 and the replica 20 asdescribed below. The stop members 39 are then allowed to harden. Oncehardened, the stop members 39 have a gingival or tooth-facing surfacethat matches the occlusal surface of the facing occlusal section of thereplica tooth or teeth 22.

A matrix material is then applied, either to the replica 20 or to thechannel of the tray 30. For example, if the matrix material isrelatively viscous and resembles a semi-liquid or gel, the matrixmaterial may be applied to the replica 20 as it appears in FIG. 5, usinga syringe, brush or other technique. Alternatively, if the matrixmaterial has a relatively low viscosity and resembles a liquid, it maybe preferable to invert the tray 30 such that the open side of thechannel of the tray 30 is facing upwardly as shown in FIG. 6. If thetray 30 is inverted, the tray 30 is not initially trimmed along theoutermost distal sides (corresponding to the ends of the dental arch) sothat the liquid matrix material is contained within the tray channel.

Subsequently, the replica 20 is positioned in the tray 30 such that thematrix material 40 is received in the channel of the tray 30 and betweenthe tray 30 and the replica 20. As shown in FIG. 6, the matrix material40 surrounds the appliance 34 and also extends along the labial andlingual surfaces of the replica tooth 22. Moreover, the matrix material40 extends along the bottom and side wall surfaces of the tray 30. Thestop members 39 serve to properly position the tray 30 from the externalsurfaces of the replica teeth 22 as the matrix material 40 is receivedin the tray channel. The matrix material 40 is then allowed to harden.

Preferably, the matrix material 40 surrounds each appliance 34 and theentire replica arch 20 except in areas near the stop members 39, whichremain in contact with the occlusal sections of the replica 20.Preferably, the matrix material 40 and the stop members 39 chemicallybond to each other as the matrix material 40 has hardened, so that thestop members 39 are not unintentionally detached during the subsequentsteps.

Preferably, the matrix material 40 has a relatively low viscosity beforehardening so that intimate contact between the matrix material 40 andeach appliance 34 is assured. In this manner, the matrix material 40 isable to substantially penetrate in various recesses, cavities and otherstructural features of each appliance 34 so that a secure connectionbetween the appliance 34 and the matrix material 40 can be established.An example of a suitable matrix material having a relatively lowviscosity is a silicone material such as “RTV615” silicone material fromGeneral Electric as mentioned above. The relatively low viscosity ofthis silicone matrix material also assures that the matrix material willassume a configuration that closely matches the shape of the adjacentsurfaces of the replica teeth 22.

Alternatively, the matrix material 40 may comprise a dental impressionmaterial or a bite registration material. Suitable materials includepolyvinylsiloxane impression material, such as Memosil 2 brand vinylpolysiloxane material from Heraeus Kulzer Inc., or Peppermint Snap brandclear bite registration material from Discus Dental. If a light-curableadhesive is to be used for bonding the appliances 34 to the patient'steeth, the matrix material 40 is preferably optically clear andtransmits actinic radiation without substantial absorption.

Once the matrix material 40 has hardened, the tray 30, together with thematrix material 40 and the appliances 34, are detached from the replica20. The use of the release agent as mentioned above helps facilitatedetaching of the appliances 34 from the corresponding replica teeth 22.Excess material of the tray 30 and excess matrix material 40 are thentrimmed as desired as discarded. The resultant trimmed transferapparatus 44 (comprising the tray 30, the matrix material 40, the stopmembers 39 and the appliances 34) is shown in cross-sectional view inFIG. 7.

Once the patient has returned to the office, the patient's teeth thatare to receive appliances are isolated using cheek retractors, tongueguards, cotton rolls, dry angles and/or other articles as needed. Theteeth are then thoroughly dried using pressurized air from an airsyringe. Etching solution (such as 3M Unitek Transbond XT brand etchinggel) is then dabbed onto the teeth in the general area that is to becovered by the appliances 34, taking care to prevent the etchingsolution from flowing into interproximal contacts or engaging the skinor gingiva.

After the etching solution has remained on the selected tooth surfacesfor a period of approximately thirty seconds, the solution is rinsedaway from the teeth with a stream of water for fifteen seconds. Thepatient's teeth are then dried by the application of pressurized airfrom an air syringe (for example, for a time period of thirty seconds)and excess water is removed by suction. Care should also be undertakento ensure that the saliva does not come in contact with the etchedenamel surfaces. Cotton rolls and other absorbent devices are replacedas needed, again making sure that saliva does not contact the etchedenamel. Air from the air syringe may then be applied to the teeth againto ensure that the teeth are thoroughly dried.

Next, a bonding adhesive is applied to the hardened adhesive 36 and/orthe selected areas of the patient's teeth. Optionally, the adhesive is atwo-component adhesive as depicted in FIG. 7. For example, the firstcomponent 41 is a Transbond brand XT moisture insensitive primer, andthe second component 43 is Transbond brand Plus self-etching primer,both from 3M Unitek. The first component 41 is applied to the hardenedadhesive 36 and the second component 43 is applied to the area of thepatient's tooth that is to receive the appliance 34. In FIG. 7, thepatient's tooth is designated by the numeral 42.

After the first component 41 has been applied to the hardened adhesive36 and the second component 43 has been applied to the correspondingarea of the patient's tooth 42, the tray 30 is then positioned over thecorresponding teeth and seated, optionally with a swinging, hinge-typemotion. Since the shape of the cavity of the matrix material 40 and thestop members 39 together match the shape of the underlying teeth, theappliances 34 are simultaneously seated against the underlying teeth 42at precisely the same locations corresponding to the previous positionof the appliances 34 on the replica 20. Preferably, the tray 30 has ashape that is complemental to the patient's tooth structure, and hassufficient stiffness to press the appliances 34 against the teeth 42 asthe adhesive cures without the application of external pressure.However, as an option, external pressure may also be applied to theocclusal, labial and buccal surfaces of the tray 30 until such time asthe bonding adhesive has sufficiently hardened. For example, fingerpressure may be used to firmly press the appliances 34 against theenamel surfaces of the patient's teeth 42.

Other examples of suitable two-component chemical curing adhesivesinclude Sondhi brand Rapid-Set indirect bonding adhesive, Unite brandadhesive and Concise brand adhesive, all from 3M Unitek. Alternatively,a resin-modified glass ionomer cement may be employed.

Once the bonding adhesive has hardened, the tray 30 is carefully removedfrom the patient's dental arch. Preferably, the tray 30 is firstseparated from the matrix material 40, which remains in place over thedental arch along with the appliances 34. Next, the matrix material 40is detached from the appliances 34. Optionally, a hand instrument suchas a scaler may be used to help hold each appliance 34 against thesurface of the respective tooth 42 of the patient as the matrix material40 is peeled away from the appliances 34. However, in instances where arelatively soft matrix material is employed or otherwise readilyreleases from the appliances 34, the use of a scaler to help avoidfracturing the fresh adhesive bond is optional.

As another option, the tray 30 may be separated from the matrix material40 before the bonding adhesive has hardened. This option is particularlyuseful when the bonding adhesive is a light-curable adhesive.

Once the matrix material 40 has been detached from the appliances 34, anarchwire is placed in the slots of the appliances 34 and ligated inplace. Suitable ligation devices include tiny, elastic O-rings as wellas sections of wire that are tied in a loop around the appliances 34. Asanother option, the appliances 34 may be self-ligating appliances thatinclude a latch for releasably engaging the archwire such as thosedescribed in U.S. Pat. No. 6,302,688 and PCT Publication No.WO02/089693.

As can be appreciated, the hardened adhesive 36 provides a contouredbonding surface for the base of the corresponding appliance 34. Theconfiguration of this bonding surface closely matches the shape of thepatient's tooth surface and consequently facilitates the subsequent bond(using the bonding adhesive components 41, 43) that is establishedbetween the appliance 34 and the tooth 42. The bonding surface reducesthe likelihood that the appliance 34 will become unintentionallydetached from the tooth during the course of treatment.

The use of the spacer material 26 in combination with the stop members39 in the method described above is a significant advantage in that anappropriate region for receiving matrix material 40 in the tray 30 isprovided. The spacer material 26 and the stop members 39 can be shapedas needed to provide precisely the volume and configuration of region asmay be desired. For example, the spacer material 26 and the stop members39 may help ensure that a uniform thickness of matrix material issubsequently provided around the substantial extent of the tooth 42 withthe exception of the areas adjacent the appliance 34 and the occlusalsection of the dental arch adjacent the stop members 39.

Moreover, the use of the spacer material 26 facilitates the use of amatrix material having a relatively low viscosity, such as a matrixmaterial having a liquid consistency. The tray 30 is relatively stiff,and consequently maintains its shape during forming of the matrixmaterial 40. The transfer apparatus 44 is constructed such that the tray30 (other than the stop members 39) does not directly contact thepatient's teeth or gingival tissue. Instead, only the matrix material 40and the stop members 39 come into contact with the patient's teeth.

Another advantage of the present invention is that the relatively softmatrix material 40 is flexible and can accommodate a limited amount oftooth movement. For example, the teeth of the patient may have slightlyshifted between the time that the impressions are taken and the timethat the transfer apparatus 44 is fitted in the patient's oral cavityfor bonding the appliances 34. The matrix material 40 has sufficientflexibility to comply with small shifts or adjustments in the patient'stooth positions, so that the appliances 34 are properly bonded to theintended, pre-determined locations on the patient's tooth.

The matrix material 40 preferably has a viscosity before curing that isless than about 60,000 cp. More preferably, the matrix material 40 has aviscosity before curing that is less than about 25,000 cp. Mostpreferably, the matrix material 40 has a viscosity before curing that isless than about 8000 cp. Once hardened, the matrix material 40 has aShore A hardness that is in the range of about 10 to about 80, morepreferably in the range of about 30 to about 60 and most preferably inthe range of about 40 to about 50.

The stop members 39 are relatively inflexible and have a Shore Ahardness that is greater than the Shore A hardness of the matrixmaterial 40. Preferably, the stop members 39 have a Shore A hardnessthat is greater than about 60 and more preferably is greater than about90.

The use of the spacer material 26 enhances control over construction ofthe transfer apparatus, including the resultant shape of the tray 30 andthe contained matrix material 40. For instance, the spacer material 26enables the resultant thickness of the matrix material 40 to berelatively uniform and preferably relatively thin. This uniformthickness of relatively small dimension facilitates curing of aphotocurable adhesive used to bond the appliances to the patient'steeth. Specifically, when a light-curable adhesive is used to bond theappliances 34 to the patient's teeth, the uniform thickness of matrixmaterial 40 helps to ensure that the light-curable adhesive beneath eachappliance 34 is sufficiently cured to the same extent from one appliance34 to the next. In this manner, the user need not compensate for varyingthicknesses of matrix material and the curing times associated with eachquantity of adhesive need not vary from one appliance 34 to the next.

Another embodiment of the invention is illustrated in FIGS. 8 and 9.Except as described below, this embodiment is identical to theembodiment set out above in connection with FIGS. 1-7.

In the embodiment illustrated in FIGS. 8 and 9, a spacer material 26 ais similar to the spacer material 26 except that the spacer material hasone or more openings 29 a that extend along the occlusal sections of thereplica teeth 22. For example, the spacer material 26 a may have threeopenings 29 a that are located (with respect to the replica 20) inapproximately the same positions as the stop members 39 shown in FIG. 5.An interconnecting web (not shown) of the spacer material 26 a extendsbetween adjacent openings 29 a and over remaining regions of theocclusal sections of the replica teeth 22. The spacer material 26 a alsoincludes cavities (such as cavity 28 a) that are similar to the cavities28 described above.

Subsequently, a tray 30 a is formed over the spacer material 26 a(including over the openings 29 a) as shown in FIG. 9. This formingprocess is essentially the same as the forming process described inconnection with FIG. 4, except that in this instance a portion of thetray material is drawn into the openings 29 a and contacts the adjacent,occlusal sections of the replica teeth 22. Each of these portions thatare drawn into the openings 29 a provides a stop member 31 a that, inuse, functions in a manner similar to the stop members 39 set out above.However, since the stop members 31 a are integrally connected to abottom wall portion of the tray 30 a and together form a single, unitarybody, the handling of separate components during assembly of thetransfer apparatus is eliminated.

A variety of other embodiments are also possible and will be apparent tothose skilled in the art. For example, a bonding composition may beapplied to the base of each appliance 34 by the manufacturer and thenpackaged in a container for shipment to the practitioner, as describedin pending U.S. patent application Ser. No. 10/678,286 entitled“Apparatus for Indirect Bonding of Orthodontic Appliances and Method ofMaking the Same”. As a result, the practitioner can simply remove thetransfer apparatus from the container and immediately place theappliances on the patient's teeth. Additionally, the bonding compositionof at least one appliance 34 may differ from the bonding composition ofat least one other appliance 34 in the transfer apparatus in terms ofcomposition, properties or characteristics, as described in pending U.S.patent application Ser. No. 10/742,561 entitled “Packaged OrthodonticAssembly with Adhesive Precoated Appliances”, such that the bondingcomposition can be tailored to enhance the bond between the particularselected appliance 34 and its intended tooth.

Additionally, the transfer apparatus may be used for bonding only asingle appliance to a patient's tooth. For example, a portion of thetransfer apparatus described above may be used to bond a singleappliance to a single tooth subsequent to the time that other appliancesare bonded, such as in instances where access to the tooth is initiallyhindered by other teeth. As another example, a portion of the transferapparatus described above may be used to re-bond an appliance that hasunintentionally debonded from the tooth, or to bond a new appliance to atooth to replace the original appliance.

All patents, patent applications and other publications identifiedherein are expressly incorporated by reference into this disclosure.Moreover, a number of other variations, modifications and additions arealso possible without departing from the spirit of the invention.Accordingly, the invention should not be deemed limited to the specificembodiments described above, but instead only by a fair scope of theclaims that follow and their equivalents.

1. A method of making transfer apparatus for orthodontic indirectbonding comprising: providing a replica of a patient's dentition;applying a spacer material over the replica of the patient's dentition,wherein the spacer material has at least one cavity before the spacermaterial is applied over the replica, and wherein the at least onecavity has a shape for complementally receiving an orthodonticappliance; placing the orthodontic appliance in the at least one cavityof the spacer material in an orientation such that a base of theappliance contacts a replica tooth of the replica dentition; temporarilyfixing the base of the appliance to the replica tooth of the replica;forming a tray over the spacer material; removing the tray from thespacer material; detaching the spacer material from the replica;directing a quantity of matrix material onto at least one of the trayand the replica; and placing the tray over the replica such that thematrix material is between the tray and the replica.
 2. A method ofmaking transfer apparatus for orthodontic indirect bonding according toclaim 1 wherein the act of forming a tray over the spacer materialincludes the act of forming the tray over the spacer material after thebase of the appliance is temporarily fixed to the replica tooth of thereplica.
 3. A method of making transfer apparatus for orthodonticindirect bonding according to claim 1 wherein the act of directing aquantity of matrix material onto at least one of the tray and thereplica includes the act of at least partially surrounding theorthodontic appliance with the matrix material.
 4. A method of makingtransfer apparatus for orthodontic indirect bonding according to claim 1wherein the Shore A hardness of the matrix material is in the range ofabout 10 to about
 80. 5. A method of making transfer apparatus fororthodontic indirect bonding according to claim 1 wherein the Shore Ahardness of the matrix material is in the range of about 30 to about 60.6. A method of making transfer apparatus for orthodontic indirectbonding according to claim 1 wherein the matrix material is a curablematerial and has a viscosity before curing of less than about 60,000 cp.7. A method of making transfer apparatus for orthodontic indirectbonding according to claim 1 wherein the matrix material is a curablematerial and has a viscosity before curing of less than about 25,000 cp.8. A method of making transfer apparatus for orthodontic indirectbonding according to claim 1 and including the act of moving thetransfer apparatus into a patient's oral cavity in order to locate theorthodontic appliance adjacent one of the patient's teeth.
 9. A methodof making transfer apparatus for orthodontic indirect bonding accordingto claim 1 wherein the spacer material includes a number of cavities,each adopted to receive a respective orthodontic appliance.
 10. A methodof making transfer apparatus for orthodontic indirect bondingcomprising: providing a replica of a patient's dentition; applying aspacer material over the replica of the patient's dentition, wherein thespacer material has at least one cavity before the spacer material isapplied over the replica, and wherein the at least one cavity has ashape for complementally receiving an orthodontic appliance; placing theorthodontic appliance in the at least one cavity of the spacer materialin an orientation such that a base of the appliance contacts a replicatooth of the replica dentition; forming a tray over the spacer material;removing the tray from the spacer material; detaching the spacermaterial from the replica; directing a quantity of matrix material ontoat least one of the tray and the replica; placing the tray over thereplica such that the matrix material is between the tray and thereplica; and including the acts of obtaining digital data representingat least part of the configuration of the patient's dentition, andmaking the spacer material using the digital data.
 11. A method ofmaking transfer apparatus for orthodontic indirect bonding according toclaim 10 wherein the act of making the spacer material includes the actof using a rapid prototyping process.
 12. A method of making transferapparatus for orthodontic indirect bonding according to claim 10 whereinthe act of making the spacer material includes the act of using astereolithography process.
 13. A method of making transfer apparatus fororthodontic indirect bonding according to claim 10 and including the actof using computer software to determine the location of the cavity inthe spacer material.
 14. A method of making transfer apparatus fororthodontic indirect bonding according to claim 13 wherein the act ofusing computer software to determine the location of the cavity in thespacer material includes the act of relating the location of the cavityin the spacer material to the patient's dentition.
 15. A method ofmaking transfer apparatus for orthodontic indirect bonding according toclaim 1 comprising: providing a replica of a patient's dentition;applying a spacer material over the replica of the patient's dentition,wherein the spacer material has at least one cavity before the spacermaterial is applied over the replica, wherein the at least one cavityhas a shape for complementally receiving an orthodontic appliance andwherein the cavity has a facial side that is closed; placing theorthodontic appliance in the at least one cavity of the spacer materialin an orientation such that a base of the appliance contacts a replicatooth of the replica dentition; forming a tray over the spacer material;removing the tray from the spacer material; detaching the spacermaterial from the replica; directing a quantity of matrix material ontoat least one of the tray and the replica; and placing the tray over thereplica such that the matrix material is between the tray and thereplica.
 16. A method of making transfer apparatus for orthodonticindirect bonding according to claim 1 comprising: providing a replica ofa patient's dentition; applying a spacer material over the replica ofthe patient's dentition, wherein the spacer material has at least onecavity before the spacer material is applied over the replica, whereinthe at least one cavity has a shape for complementally receiving anorthodontic appliance and wherein the cavity has a facial side that isinitially open; placing the orthodontic appliance in the at least onecavity of the spacer material in an orientation such that a base of theappliance contacts a replica tooth of the replica dentition; forming atray over the spacer material; removing the tray from the spacermaterial; detaching the spacer material from the replica; directing aquantity of matrix material onto at least one of the tray and thereplica; and placing the tray over the replica such that the matrixmaterial is between the tray and the replica.
 17. A method of makingtransfer apparatus for orthodontic indirect bonding according to claim16 and including the act of closing the facial side of the cavity afterthe appliance has been placed in the cavity.
 18. A method of makingtransfer apparatus for orthodontic indirect bonding according to claim 1wherein the spacer material has a cavity corresponding to eachorthodontic appliance on the patient's dentition.
 19. A method of makingtransfer apparatus for orthodontic indirect bonding comprising:providing a replica of a patient's dentition; applying a spacer materialover the replica of the patient's dentition, wherein the spacer materialhas at least one cavity before the spacer material is applied over thereplica, and wherein the at least one cavity has a shape forcomplementally receiving an orthodontic appliance; placing theorthodontic appliance in the at least one cavity of the spacer materialin an orientation such that a base of the appliance contacts a replicatooth of the replica dentition; forming a tray over the spacer material,wherein the act of forming the tray over the spacer material includesthe act of softening tray material; removing the tray from the spacermaterial; detaching the spacer material from the replica; directing aquantity of matrix material onto at least one of the tray and thereplica; and placing the tray over the replica such that the matrixmaterial is between the tray and the replica.
 20. A method of makingtransfer apparatus for orthodontic indirect bonding according to claim 1wherein the act of forming the tray over the spacer material includesthe act of using negative pressure to draw tray material into intimatecontact with the spacer material.
 21. A method of making transferapparatus for orthodontic indirect bonding according to claim 1 whereinthe act of forming the tray over the spacer material includes the act offorming the tray while the appliance is in contact with the replicatooth.
 22. A method of making transfer apparatus for orthodonticindirect bonding comprising: providing a replica of a patient'sdentition; obtaining a set of digital data representing the shape of thepatient's dentition; making a spacer material using the digital data ina rapid prototyping process, wherein the act of making a spacer materialincludes the act of making a number of cavities each positioned in alocation that corresponds to the subsequent desired location of anorthodontic appliance on the patient's dentition; subsequently applyingthe spacer material to the replica of the patient's dentition; forming atray over the spacer material; removing the tray from the spacermaterial; detaching the spacer material from the replica; directing aquantity of matrix material onto at least one of the tray and thereplica; and placing the tray over the replica such that the matrixmaterial is between the tray and the replica.
 23. A method of makingtransfer apparatus for orthodontic indirect bonding according to claim22 and including the act of placing an orthodontic appliance in at leastone cavity of the spacer material such that the appliance is in contactwith the replica.
 24. A method of making transfer apparatus fororthodontic indirect bonding according to claim 22 and including the actof placing an orthodontic appliance next to the replica, and wherein theact of directing a quantity of matrix material onto at least one of thetray and the replica includes the act of at least partially surroundingthe orthodontic appliance with the matrix material.
 25. A method ofmaking transfer apparatus for orthodontic indirect bonding according toclaim 22 wherein the act of making a spacer material using the digitaldata in a rapid prototyping process includes the act of using at leastone of a stereolithography process and a thermojet printing process.